(a) Field of the Invention
The present invention relates to a method for establishing a connection over user computers in heterogeneous networks, and a domain name system proxy server for controlling the same. More particularly, the present invention relates to a method for supporting communication between user computers included in Internet-compatible heterogeneous networks through a gateway based on an Internet public network.
(b) Description of the Related Art
The address shortage problem in Internet protocol version 4 (IPv4) was brought out about two decades ago, and many solutions have been suggested since then and they have been integrated into Internet protocol version 6 (IPv6).
The IPv6 provides a larger address space, but the use of the address space is limited.
Accordingly, new schemes have been suggested and standardized. Among the new schemes, Network Address Translation (NAT) is a method by which IP addresses are mapped from one group to another, and are transparent to end users by using a residual network address.
The NAT provides a connection from an IPv4 private user-network to an IPv6 public network using one or few public network addresses through a gateway without modification of protocol stacks in a user's computer, but it depends on end-to-end consistency.
Similar to the NAT, a Realm Specific Internet Protocol (RSIP) has been suggested as an IP address translation technique, as an alternative to the NAT. The RSIP has been standardized for solving the problem of the NAT, but it also has a problem of requiring a change of a protocol stack in a user's computer.
A NAT Protocol Translation (NAT-TP) is a method for translating network addresses and TCP/UDP ports into TCP/UDP ports that correspond to one network address, and providing a transparent connection to IPv4 public network users in the IPv6 network by using the NAT.
A Translating, Relaying Internet Architecture Integrating Active Directories (TRIAD) connects two IPv4 private user-networks through gateways based on an IPv4 public network.
Therefore, communication between one private user-network and another private user-network can be achieved. However, similar to the RSIP, the TRAID also requires protocol stack modification within a user-computer and therefore it is inappropriate for common use.
Therefore, the prior arts cannot support communication between Internet-compatible heterogeneous user-networks due to the protocol stack modification and end-to-end consistency requirements.
For example, as shown in FIG. 1, the prior arts cannot support communication between one IPv4 private user-network and another IPv4 private user-network, communication between one IPv4 public user-network and an IPv4 private user-network, communication between an IPv6 network and an IPv4 private user-network, and communication between an IPv4 public user-network and an IPv6 user-network.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.